Monday November 17 2014
The Mediterranean diet can lower cholesterol
"A Mediterranean diet may be a better way of tackling obesity than calorie counting, leading doctors have said," BBC News reports.
In a recently published editorial, they also argue the NHS should do more to encourage its staff to eat more healthily.
As this was an editorial, and not new evidence, it cannot prove the Mediterranean diet, which is characterised by vegetables, fruits, beans, whole grains, olive oil and fish, is "best". But the article does raise some interesting points.
They argue that the obesity epidemic is intrinsically linked to an unhealthy food environment – one in which easy access to cheap, high-energy, nutrient-poor junk food promotes poor choice by default.
Doctors cannot just issue calorie control and exercise advice ("eat less, move more"), but need to encourage healthier eating overall. The Mediterranean diet has been linked to improved cardiovascular health, as we discussed in 2013.
The authors also point out the need to promote healthy eating within the NHS – for example, providing healthy meal options for both patients and staff.
That way, healthcare professionals can inform patients and the public about how diet can improve health by leading by example.
Where does the story come from?
The story follows an editorial published in the peer-reviewed Post Graduate Medical Journal. It was authored by three professionals with affiliations to Frimley Park Hospital in Surrey, the Academy of Medical Royal Colleges in London, and NHS England. The authors declare no conflicts of interest.
The authors discuss the current obesity epidemic and the effect that different approaches can have on this, referencing various publications.
They do not provide any methods for identifying the various studies they reference, and this does not appear to be a systematic review.
It is not known whether all the literature relevant to the issue of healthy eating has been considered.
Therefore, this editorial must be considered as the views and opinions of the authors based on their knowledge of the literature and expert opinion. We do not know whether another systematic review of the subject would reach the same conclusions.
What do the researchers say about the obesity problem?
The researchers explain how the obesity epidemic currently costs the NHS about £6 billion a year, while obesity-related diseases such as diabetes cost even more.
Our diet is a powerful determinant of our weight and health. However, as the authors consider, the decisions that we make about the food we buy is often made without full conscious awareness, and we can be seduced by the brightly coloured packaging of confectionery at the till.
The authors discuss foods that have been the particular focus of attention in trying to reduce the risk of cardiovascular disease.
Fruit, vegetables, nuts, olive oil and oily fish – common in Mediterranean cuisine – contain α-linoleic acid, polyphenols and omega-3 fatty acids, which are believed to reduce inflammation and the formation of fatty blood clots in the arteries. This reduces the risk of heart diseases, such as heart attacks.
The researchers say it's estimated that increasing the world's consumption of fruit and vegetables by one portion a day, and nuts by two servings a day, would prevent 5.2 million cardiovascular deaths worldwide within a year.
It is also estimated that reducing people's sugary drink consumption by 15% would, within a year, prevent 180,000 people from becoming obese in the UK, and save the NHS £275 million.
The researchers say real progress will only be made when "the need for a healthier food environment" is understood. As they say, collective action is needed so that an individual's choices about what to eat default to healthy options rather than junk food: "healthy choice must be the easy choice".
There is currently an oversupply of cheap, high-energy, nutrient-poor food, such as confectionery, crisps and sugary drinks, in vending machines, food trollies and food outlets in NHS hospitals – the places that should be promoting positive healthy messages.
Not only does this impact on the choice of patients and visitors, but also NHS staff – half of whom are estimated to be overweight or obese.
As the researchers also consider, the effects of regular physical activity will be undermined if someone has a poor diet: "you can't outrun a bad diet".
What do they say about specific diets?
The researchers discuss "weight cycling" – rapid loss and regain – and how this has been associated with high blood pressure, poor blood sugar and blood fat control, and poor overall cardiovascular outcomes.
US research shows most people on rapid diets regain most of their lost weight, and two-thirds do not gain any health benefit.
In contrast, they discuss one trial that randomised 7,500 high-risk adults to either the Mediterranean diet (41% total fat, supplemented with extra virgin olive oil or nuts) or low-fat dietary advice.
They report the Mediterranean diet was associated with a 30% reduction in major cardiovascular disease events within three months.
It is unclear how this effect was calculated and whether it was compared with the low-fat group. The researchers report these reductions in cardiovascular disease risk were irrespective of weight.
They also report another study, which showed how adopting a Mediterranean diet after a heart attack is almost three times as effective as a statin at reducing mortality.
The researchers also mention another trial, which found an energy-unrestricted, high-fat, low-refined carbohydrate diet (restricting carbohydrates without fibre) resulted in more weight loss and a better blood fat profile one year later when compared with a low-fat diet.
What suggestions to the authors make?
The researchers suggest that introducing evidence-based nutrition into the training of doctors and nurses would increase their understanding of the science of healthy eating, and also allow better-informed nutrition discussion between health professionals and patients.
They also say the NHS as an employer is in a key position to set a national example by supporting 1.4 million staff to stay healthy and serve as "health ambassadors" in their local communities.
The researchers say it is time to get across the evidence base that healthy dietary change rapidly improves outcomes, and put this into the heart of the NHS.
They report the key recommendations of the "Five Year Forward View" published by NHS England and partner organisations in October 2014, which set out a vision for the future of the NHS:
- Make information about the evidence base for healthy diets easily available to NHS staff and patients.
- NHS employers to implement the Workplace Wellbeing Charter and require commissioners to consider this when assessing tenders.
- Implement National Institute for Health and Care Excellence (NICE) guidance on promoting healthy workplaces throughout the NHS.
- Reduce access to processed foods high in fat, salt and sugar on NHS premises.
- Provide healthy diet options for all staff, including night staff.
- Call for NHS institutions to objectively monitor and publish sales and quantities of foods deemed unhealthy, in addition to the degree of adherence to national food standards.
The focus of this research is on changing the dietary environment to a healthy rather than an unhealthy one, particularly within the NHS.
The media has focused on the Mediterranean diet, but this is not the sole focus of the study. Reports on the Mediterranean diet come from two brief references to two trials within the editorial.
From the information provided in this editorial alone, it is not possible to comment on the reliability and comprehensiveness of all the information provided.
As stated, this does not appear to be a systematic review. Therefore, without knowing the methods the researchers used, it's not possible to say whether all the relevant evidence relating to the issue of healthy eating has been considered.
With only examples of a few dietary trials discussed, we do not know whether all the evidence relevant to the comparative effectiveness of different dietary approaches (for example, Mediterranean versus low fat) has been examined.
Without looking at the individual studies behind the data in this editorial, it is also not possible to review how accurate and reliable the effectiveness data and estimates are likely to be, or how they were calculated – for example, estimates on reduction of cardiovascular deaths and obesity with specific alterations to food intake.
Nevertheless, the overall message of this editorial – to make the dietary environment a healthier one – is sensible and consistent with recommendations made by other health organisations.
Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on Twitter. Join the Healthy Evidence forum.